Blue Book "Disability Evaluation under Social Security."  This publication explains the whole process from a doctors point of view. The publication is in the Adobe Reader format. 
http://www.ssa.gov/disability/bluebook/ 

Adobe Reader download link if you don't have it installed: http://www.adobe.com/products/acrobat/readstep2.html

Family members may also be able to receive benefits if you are found to be disabled.  Qualifying spouse, child, disabled child may be able to receive up to 50% of your benefit.  This is very important and highly overlooked benefit.  http://www.ssa.gov/dibplan/dfamily.htm

If you were found to be disabled your SSDI benefits will start the sixth full month after they found you were disabled.  To calculate your benefits:  http://www.ssa.gov/planners/calculators.htm

When will your case be reviewed to determine if you are still disabled? That depends on a number of facts.  The intervals between reviews will vary depending on the impairment, severity, and if improvement is expected. Generally every:

• 6 to 18 months after you became disabled if your condition was expected to improve.

• Once every three years if there is a possibility of improvement but improvement cannot be predicted.

• Once every 7 years if the disability is not expected to improve.

Your doctor will determine the severity of your condition.  For more information see this government publication: http://www.ssa.gov/pubs/10068.html

Have a question concerning Social Security?  The government has a question and answer section.  http://ssa-custhelp.ssa.gov

Need a Social Security form?  This page will assist you in finding the form you need. http://www.ssa.gov/online/forms.html#Medicare

At this point I hope I have provided the necessary information to get you started toward applying for government disability.   In the next section is information on what to do if you are denied government disability.

You have been denied Social Security benefits - what can you do?  There are a number of processes available including: reconsideration (you will have someone decide your case which had no part in the first decision), a hearing (the hearing process begins after an applicant for benefits has been denied at the initial and reconsideration levels), an appeal (the Appeals Council review process generally begins after an application for benefits has been denied at the initial, reconsideration, and hearing levels).   A brief explanation of the processes and links to the government sites for each: CHANGES have been made to this process: see below.  More information to follow.

•      Reconsideration is a complete review of your claim by someone at Social Security (or at the state disability determination services if you are appealing a disability decision) who had no part in the first decision.   That person will look at all the evidence used to make the original decision, plus any new evidence. UPDATE: Starting January 1, 2006 if Medicare denies your first appeal, you can request a "reconsideration" (replacing the Part B "fair hearing"). You will have six months (180 days) to file after Medicare denies your initial appeal. This second level of appeal will be handled by a new group of Medicare contractors called Qualified Independent Contractors (QICs), who will review your medical file to determine if the service in question should be covered. You will not appear in person for the reconsideration.
  http://www.ssa.gov/pubs/reconsideration

• If you disagree with the hearing decision made by the law judge, you may ask for a review by Social Security's Appeals Council.   The Appeals Council looks at all requests for review, but it may deny a request if it believes the hearing decision was correct.   If the Appeals Council decides to review your case, the Council will either decide your case itself or issue an order returning your case to an administrative law judge for further action.
  http://www.ssa.gov/appeals/appeals_process.html

• The center for Medicare Advocacy  Subjects include: litigation, Medicare Part D, and fair access to health care.
  http://www.medicareadvocacy.org/default.htm

An excellent resource for individuals seeking disability or those who receive benefits, is the government's "Red Book".

 Some of the important topics are:

• Ticket to work program - A program to aid in rehabilitation and training with many benefits while you are being trained.

• Trial work Period - Enables you to have employment and receive your SSDI while you are attempting to work again.

• Unsuccessful work attempt - An unsuccessful work attempt is an effort to do substantial work, in employment or self-employment, that you stopped or reduced to below the SGA (Substantial Gainful Activity) level after a short time (6 months or less).
  http://www.socialsecurity.gov/redbook/